Motorcycle Repair: 81 Honda GL1100I, added accessories, voltage readings

Question
i have a 1981 GL1100I bike w/29,000 miles and have been working on getting it ready for the road. I am having a problem with the charging system. My battery keeps discharging so I checked the out put to the battery with a volt meter and it reads 12.50 volts.the repair manual says it should be 14 volts at 3000 rpm , so I checked the alt and regulator with my ohms meter as the book called for and it does not show an open or shorted problem. So i bought a used regulator and the charging came up to 14 volts but the new used regulater get very hot and the voltage jumps from 14 to 12 volts and the lights flicker.
I am not sure what to do next hope you may have some Idea.
Thank you for any help.


Answer
Hi Sonny!

Ok... for simplicity reasons, I will answer this question as if the bike was brought into my shop for repair. The first thing I'm gonna do is make sure the battery is good and powerful. I would charge it overnight and put a load checker to it, if it passes that test, I will recharge it again and put it in the bike. Next, I take voltage readings. The first one is with the battery in the bike but with the engine off and the key off. This establishes our baseline voltage. Let's say it reads 12.8 volts. Next, I start the bike and let it run for about 20 - 30 seconds and take a reading (with the engine idling). This reading needs to be higher than the baseline voltage. If it is the same or less, then you for sure have a problem. Now I increase the throttle and watch what happens to the reading. Sometimes it goes up sometimes it stays the same. What is important here is that it never drop below the baseline voltage. I know the manuals state what the readings should be, but that is under ideal conditions, and the manual can't account for added accessories (especially on a GoldWing). I've seen plenty of bikes with a baseline reading of 12.5v, which goes up to 14.2 at idle, but then drops to 13.8v at 4000rpm or higher. Although the manual would say you have a problem, you really don't. Now... if I do the above voltage tests and the charging system fails the test... I would do the tests that you already did. The ohm and continuity tests. Keep in mind, that just because the components pass that test does not mean they are performing properly. Those tests will only locate dead opens and dead shorts... they do not give an accurate account of what is happening under load. So now I would shut down the engine and separate the connector that connects the alternator (stator) to the wiring harness. It is usually a three prong connector at the end of the wires that come out of the engine where the stator (alternator) is located. The wires will be either all yellow or all white. Once disconnected, start the bike and set your volt meter to AC voltage (range set at a minimum of 100VAC) and take voltage readings between 2 of the three wires. then switch to a different set of two wires, and finally the third set of two wires. (I know that sounds confusing). Look at it like this... If you labeled each wire 1,2 & 3, then what you are doing is taking a reading between 1 & 2, then 1 & 3, then 2 & 3. Your alternator is a three phase AC type. Each one of those readings should be roughly the same voltage (+ or - a few volts) and need to be more than 20vac at idle. If any of those readings are less than 20vac at idle, then the stator is faulty. If the stator is ok, and the battery is known to be good, then the only other component in the equation is the Rectifier/Regulator. But keep in mind that there are wires and connectors in between all these components, and on a bike that old, it is conceivable that a wire or a connector is to blame. Gee Sonny... I'm sorry to make you read this novel, but I wanted to be clear and concise. The charging system on your bike is really quite simple, but is subject to the smallest problem... sometimes something as simple as a bad battery terminal connection can drive ya crazy. Hope this has been helpful and gets ya all "charged" up!! Good luck and Ride Safe!!

Jack